Soil, organics, and Co2 , 13°

C Robb W. 444°

Soil is one of our most precious resources and along with many others we are treating like dirt.

* The United States is losing soil 10 times faster -- and China and India are losing soil 30 to 40 times faster -- than the natural replenishment rate.
* The economic impact of soil erosion in the United States costs the nation about $37.6 billion each year in productivity losses. Damage from soil erosion worldwide is estimated to be $400 billion per year.
* As a result of erosion over the past 40 years, 30 percent of the world's arable land has become unproductive.
( Feb 2008)

Rodale Institute has published some research cataloging the potential effects proper soil husbandry can have on global warming. Much of the information and graphics for this post is drawn from that report. It can be downloaded from their site.

Aside from the obvious benefits of growing food, providing a base for vegetation that prevents erosion, acting as a sponge to mitigate the effects of flooding, reducing pollution from agricultural runoff, the soil offers other less well known services. If treated properly soil sequesters carbon, it actually locks up more carbon than the vegetation growing on it.

"On a global scale, soils hold more than twice as much carbon (an estimated 1.74 trillion US tons) as does terrestrial vegetation (672 trillion US tons)."

This is accomplished through the buildup of humic substances, soil organic matter or SOM, in the soil that allow long term carbon storage. This SOM, which is primarily made up of carbon, is the heart and soul of organic agriculture. SOM is almost completely avoided in industrial agriculture which uses petrochemicals to replace the nutrients otherwise provided.

The naturally developed grassland soils that much of the American corn and soy crop grows in was originally comprised of 6-10% SOM. These soils have been degraded to typically 1-3% by industrial agricultural methods. Indeed, Rodales research over 27 years indicates that organic systems increased soil carbon by 30% while their similar petrochemically managed fields showed no increase in carbon.

This effect is largely down to a beneficial environment for fungi which is fostered by organic methods. No only does fungi assist in the processes necessary for carbon sequestration but,

"Mycorrhizal fungi structures enhance the ability of plant roots to access soil moisture and nutrients, produce stable compounds to sequester carbon dioxide as soil carbon, and slow decay of soil organic compounds."

Fungi is most amazing stuff. For more on that check out the work by Paul Stamets at

Additionally the practices of organic fertilization and cropping diversity stimulates carbon sequestration whereas petroleum based practices and mono cropping stimulates quick decay of SOM thus releasing carbon into the atmosphere.

Organic practices like cover crops and composting have direct benefits to the atmosphere in that they use 33% less fossil fuel in the farming practices themselves compared to petroleum fertilizer based practices. Further Rodale research has shown that,

"the use of composted manure with crop rotation in organic systems can result in carbon sequestration of up to 2000 lbs/ac/yr. By contrast, fields under standard tillage relying on chemical fertilizers lost almost 300 pounds of carbon per acre per year."

If all 43 million acres of cropland in the US were to use these methods 1.6 billion tons/yr would be sequestered, around 25% of the total US fossil fuel emissions.

Here are some more facts about Organic agriculture from the Organic Consumers Association,

* If organic farming methods were practiced on all the planet's food-growing land, it would be like taking more than 1.5 billion cars off the road.
* You can increase your antioxidant intake by 30 percent by choosing organic.
* The average child in America is exposed to five pesticides daily in their food and drinking water.
* The U.S. water system is regularly contaminated above safe limits immediately following chemical fertilizer applications to farm fields.
* Farms in developing countries that use organic techniques produce an average of 79% more than farms that don't.

So it seems clear that organic agriculture produces healthier food, more food, is far less damaging to the soil and surrounding ecosystem, and can help mitigate global warming and climate change. It looks like the sustainable choice to me.

Thanks to Rodale Institute for the report from which most of this post is drawn and the Organic Consumers Association for pointing me in that direction and for additional facts.

8 replies

C Robb W. 444°

Imagine a freight train with every boxcar filled with topsoil, that train stretches around the planet. Now imagine it stretches around the planet 18 times over. That is how much soil we loose in the continental US per year!

I heard this figure quoted in an interview with Penny Livingston Stark with the Permaculture Institute. She said it came from the Natural Resource Conservation Service at the Department of Agriculture.

Written in November 2008

Charles M. 110°

When stated in terms of trains going around the world that number sounds quite high, but it is really quite low and I would not be suprised if it is actually a lot higher.

Doing a quick calculation: The world is approx 40,000 km at the equator and a box car is approx 2.5 metres high and 3 metres wide, making the volume of the train approx 5.4 x 10^9 cubic metres. The area of USA is approx 9.8 x 10^12 square metres making the soil loss 0.0006 metres (ie 0.6 mm) (ie one fiftieth of an inch) over the whole USA.

Of course loss in agricultural areas will be higher than that and my estimate of the size of a box car might be off by a factor of two or so, but the numbers still seem pretty low.

Written in November 2008

It is time to seriously consider the use of the 'Vetiver system' (see a tried, tested and green solution to soil erosion

Written in March 2009

Charles M. 110°

Veltiver does look very interesting for many applications. It looks like it is mainly suited to tropical locations.

You need to be very careful about moving plants from one environment to another without doing significant trails and environmental assessments. For example, here in New Zealand we have a problem with gorse which was introduced from UK to make the coutryside look more English and to be used as a hedging plant. Gorse grows slowly and non-invasively in UK and the cooler areas of NZ but is a terribly invasive weed in warmer areas.

Written in March 2009

I thoroughly agree about the dangrs of introducing non-native plant specis without adequate resarch and control. The 'sunshine' cultivar of vetiver grass (scientific name: Chrysopogon zizanioides)is not invasive as evidenced by the PIER (Pacific Island Ecosystems at Risk) assessment that vetiver grass has a very low risk factor of minus 8. Even the most stringent countries will allow imports of plants with a plus 1 risk assessment.

Written in March 2009

C Robb W. 444°

Vetiver looks interesting. What uses does it have as a fiber? I saw handicrafts but that wouldn't apply everywhere. Is it profuse enough to harvest for biomass?

Written in March 2009

Vetiver is certainly very profuse, with the 'leaves' groing to up to 2 metres in height, and therefore an excellent soure of biomass. A collegue in Sardinia has recently calculated the yield on an hectare consisting of 200 rows, spaced 50cm and 100m long as yielding a total weight per hectare of the
dry mass as 50 Tonnes. Cutting off the biomass has no detrimental effect on the plant. The amount obtained per year would depend on the conditions, but it would be very reasonable to consider 2 harvests. More info on this (and photos) could be found at:

In terms of growing, vetiver has wide pH range, seems to be able to grow in any type of soil regardless of fertility and has been
found to be unaffected by the temperature as long as it doesn't freeze (but prefers sun and warmth) as high as 45 ºC.

As fibre the leaves are used in Senegal for roofing materials (see my blog) and are very long lasting. I would certainly imagine that they could be used for other fibre applications, and in India some research has been done on paper making using the leaves. Fibre boards are another application.

Written in March 2009

I have come across someone who writes about his experience of growing Vetiver in New Zealand. John Greenfield is one of the original 'vetiverists' and his knowledge is incomparable. His experience in NZ, based lagely it seems on slope protection, is as follows:

"We have been establishing the vetiver system down here in Northern New Zealand, Latitude 35 - 40 degrees South for the past 16 years. I started the way I had been using vetiver in the tropics, by planting slips - these took 3 years to establish a hedge this far south of the equator, but a good permanent hedge has been estabished. Since then we have moved to glass house potted plants grown in polybags (about 15cms in diameter by 20 deep) filled with cheap potting mix. These are produced to good healthy plants in the glass house through the winter, then at the begining of spring they are planted out as a hedge 5 pots to the metre. On road cuttings we have had great success and some great failures. The failures have been due to unseasonable weather - November December last year was very cold then January thru to May we had a severe drought. VS planted this far south of the equator cannot handle extreme stress before it has established, but once established, the hedges work perfectly. The hedges that have been established on road slips have impressed the engineers to the point that they are prepared to put up with 'gap filling' and the slow rate of establishment knowing that the end product is better than all their static measures, and certainly costs less to maintain. Initially we have to be aware of aspect by avoiding sites facing South.

What I have learned from establishing VS this far South of the Equator:- 1. You need to establish good healthy potted plants to get an effective hedge that will spread out runoff and stop rilling at the top of the slope. You have to be prepared to maintain these hedges for the first three gowing seasons - though with 'good' growing weather, we have established a permanent hedge in four months.
2. You have to be prepared to fertilise the hedge in the first two seasons using DAP (DiAmonium Phosphate)applied at the back of the hedge. 3. clipping the hedge to a height of 40 cm encourages it to tiller.

But apart from all this, we have hedges here in NZ that have been neglected once they have been established and they are surviving quite well.

The roads engineers are really impressed with the way VS can stabilise road slips, and once estasblished this stabilisation is permanent and they can move on to the next problem.

Cost comparisons - A 50 metre retainer wall requiring pile drivers, excavators, concrete and piles to stabilise a slip cost $50,000, or $1,000 a metre - we are charging $20 - 50/metre potted plants transported to the site planted, fertilised and maintained for three seasons. Our hedges stop the slip, and require no maintenance, where as their static measures at the best will last 11 years and usually need costly maintenance every year.

In temperate climates they have no other options for vegetative control that works, you just have to be patient, because once VS is established, there is nothing that compares with it for longevity and sustainability."

Written in March 2009

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